Genetic characterization of the complete genome of a highly divergent simian T-lymphotropic virus (STLV) type 3 from a wild Cercopithecus mona monkey
1 Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore MD 21205, USA
2 Global Viral Forecasting Initiative, San Francisco, CA, 94105, USA
3 Stanford University, Program in Human Biology, Stanford, CA 94305, USA
4 Laboratory Branch, Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
5 UMR 145, Institut de Recherche pour le Developement (IRD) and University of Montpellier 1, Montpellier, France
6 Centre de Recherche du Service Santé des Armées (CRESAR), Yaoundé, Cameroon
Retrovirology 2009, 6:97 doi:10.1186/1742-4690-6-97Published: 27 October 2009
The recent discoveries of novel human T-lymphotropic virus type 3 (HTLV-3) and highly divergent simian T-lymphotropic virus type 3 (STLV-3) subtype D viruses from two different monkey species in southern Cameroon suggest that the diversity and cross-species transmission of these retroviruses are much greater than currently appreciated.
We describe here the first full-length sequence of a highly divergent STLV-3d(Cmo8699AB) virus obtained by PCR-based genome walking using DNA from two dried blood spots (DBS) collected from a wild-caught Cercopithecus mona monkey. The genome of STLV-3d(Cmo8699AB) is 8913-bp long and shares only 77% identity to other PTLV-3s. Phylogenetic analyses using Bayesian and maximum likelihood inference clearly show that this highly divergent virus forms an independent lineage with high posterior probability and bootstrap support within the diversity of PTLV-3. Molecular dating of concatenated gag-pol-env-tax sequences inferred a divergence date of about 115,117 years ago for STLV-3d(Cmo8699AB) indicating an ancient origin for this newly identified lineage. Major structural, enzymatic, and regulatory gene regions of STLV-3d(Cmo8699AB) are intact and suggest viral replication and a predicted pathogenic potential comparable to other PTLV-3s.
When taken together, the inferred ancient origin of STLV-3d(Cmo8699AB), the presence of this highly divergent virus in two primate species from the same geographical region, and the ease with which STLVs can be transmitted across species boundaries all suggest that STLV-3d may be more prevalent and widespread. Given the high human exposure to nonhuman primates in this region and the unknown pathogenicity of this divergent PTLV-3, increased surveillance and expanded prevention activities are necessary. Our ability to obtain the complete viral genome from DBS also highlights further the utility of this method for molecular-based epidemiologic studies.